In ovo dexamethasone elicits an increase in ACTH-stimulated glucocorticoid release but no effects on fear behaviors in Pekin ducks.

Authors

N K Wilson, J M Schober, E M Oluwagbenga, I C von Seggern, G S Fraley

Published in

Poultry science. Volume 105. Issue 9. Pages 107052. May 02, 2026. Epub May 02, 2026.

Abstract

Heat stress is among the leading causes of stress to poultry during their productive life, leading to the loss of profit at each stage of production. This event can have profound impacts on a duck's physiology, leading to changes in their behavior and an increased response to future stressors. We have previously shown that breeder ducks exposed to heat stress deposit increased quantities of glucocorticoids in their eggs, and that is correlational to altered phenotype of the offspring. We sought to replicate those findings by increased glucocorticoid content in ovo without a parental heat stress (HS) event. Eggs were injected with either dexamethasone (Dex; = 100/treatment (1ug/ul]) or saline (Con = 100/treatment (0.1 mg/egg)), sealed with silicon glue and set to incubate and hatch following industry standards. Ducklings were separated into their respective groups (n = 50/treatment/pen). At 3 weeks of age, ducks were then given an adrenocorticotropic hormone (ACTH; 0.0625 mg/kg cosyntropin in 1.0 ml saline) challenge (n = 6/treatment) or control (1.0 ml saline per bird). Blood was collected at 0,1,2, and 4 h after injection. An isolation fear test was performed on the ducks at week 3.5 and novel environment test on weeks 1 and 5. Heterophil to lymphocyte ratio (HLR), ELISA for glucocorticoids, feed conversion ratio (FCR), and weekly body weights were all calculated and recorded. No significant differences were observed in FCR, body weights, or isolation fear test metrics such as latency to first vocalization. There were significant differences in circulating corticosterone in the Con-ACTH and Dex-ACTH groups each time point. The Con-ACTH had a significant (p < 0.05) increase after hour 1, and the Dex-ACTH groups showed a further significant (p < 0.05) increase above all other groups. Similar results were obtained with cortisol and HLR. The novel environment test showed only an age effect between weeks 1 and 5. Our results show that the in ovo glucocorticoids impact physiological, but not necessarily behavioral responses.

PMID:
42320188
Bibliographic data and abstract were imported from PubMed on 20 Jun 2026.

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